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NHTSA to require electronic stability control

Jun 23, 2015

Electronic stability control (ESC) will be required on truck tractors and certain buses manufactured on or after August 1, 2017.

In a final rule published in the June 23 Federal Register, a new Federal Motor Vehicle Safety Standard will mandate the safety feature on tractors and on buses with gross vehicle weight ratings greater than 26,000 pounds.

Petitions for reconsideration of this final rule may be submitted no later than August 7. The final rule is scheduled to take effect August 24.

The new safety standard, FMVSS 136, is designed to reduce untripped rollovers and to mitigate severe understeer or oversteer conditions that lead to loss of control. It will require the use of automatic computer-controlled braking and reduced engine torque output to achieve its objectives.

Such systems have been gaining market share on their own merit. NHTSA estimates that without the mandate, 34% of new truck tractors and 80% of new buses affected by this final rule would be equipped with ESC systems by 2018.

“We believe that, by requiring that ESC systems be installed on the rest of truck tractors and large buses, this final rule will prevent 40-56% of untripped rollover crashes and 14% of loss-of-control crashes,” the agency wrote in announcing FMVSS 136. “As a result, we expect that this final rule will prevent 1,424 to 1,759 crashes, 505 to 649 injuries, and 40 to 49 fatalities at $0.1 to $0.6 million net cost per equivalent life saved, while generating positive net benefits.”

FMVSS 136 will require ESC, rather than the less comprehensive roll-stability control.

A roll stability control (RSC) system is designed to prevent rollover by decelerating the vehicle using braking and engine torque control. Electronic stability control includes all of the functions of an RSC system plus the ability to mitigate severe oversteer or understeer conditions by automatically applying brake force at selected wheel-ends to help maintain directional control of a vehicle.